Like rings on a tree, coral exoskeletons grow in layers, helping paleoclimatologists learn about weather trends and phenomena from as many as 500 years ago. When exposed to a synchrotron – one of the world’s most powerful X-ray machines – in a Stanford University lab, the coral’s secrets become even more pronounced, revealing weather patterns and ocean temperatures down to the week, and giving researchers a highly detailed and accurate look at weather over several centuries past.